Recently, it is pointed out that to produce and consume large amount of plastics derived from fossil resources is source of environmental pollution in view of global heating and waste disposal. From this background, a demand for using biodegradable polymers and polymers derived from vegetable-origin materials is enhanced, and study and research therefor are conducted actively. Among these, aliphatic polyesters are noticed as the biodegradable materials and are expected for development to various arts because of expecting an effect for reducing environmental load by producing aliphatic polyesters derived from vegetable-origin materials. However, the aliphatic polyesters have such problems that the hydrolysis activity is high, the properties thereof are difficult to maintain under high temperature and high humidity and also generally the impact resistance is poor. Therefore, a aliphatic polyester is limited in the field-of-use when singly used.
As the method for improving the impact resistance of aliphatic polyester, there is proposed a composition comprising an aliphatic polyester and various styrene-based resin containing ABS resin (refer to Patent Documents 1 to 3). However, by the present inventors' studies there to, it has been found that there is no effect for improving the impact resistance in all resin compositions and it is difficult to obtain a resin composition having. Further, as a proposal for improving both impact resistance and rigidity, there is proposed a composition comprising polylactic acid resin and a specific rubber reinforced resin (refer to Patent Document 4). However, this composition has such problems that the elongation at break is poor and brittle fracture generates in the impact resistance test.
Patent Document 1: Japanese Patent Application Laid-Open (KOKAI) No. 2005-171205
Patent Document 2: Japanese Patent Application Laid-Open (KOKAI) No. 2006-45485
Patent Document 3: Japanese Patent Application Laid-Open (KOKAI) No. 2006-45486
Patent Document 4: Japanese Patent Application Laid-Open (KOKAI) No. 2006-137908